Sutton Salt Lake

from Wikipedia, the free encyclopedia
Sutton Salt Lake in its dry phase in mid-November 2008

The Sutton Salt Lake is the only salt lake in New Zealand and is a specialty among the salt lakes of the world due to the way it is formed.

geography

The salt lake is located on the South Island of New Zealand about 65 km northwest of Dunedin . It is located at an altitude of 250 meters in the relatively dry region of Otago . The distance to the Pacific Ocean is only 50 km. The approximately two-hectare lake can be reached via a branch off the New Zealand State Highway 87 near Sutton, about 8 km from Middlemarch .

Origin and geology

The Sutton Salt Lake was created under the special conditions of the windy, cool sea ​​climate of New Zealand's South Island and the specific geological conditions. In a only 5 meter deep rock-bedded depression , which has no inflow and no outflow, water collected, which came exclusively from the precipitation. The slate-like rock floor did not allow any contact with the groundwater. There was also no infiltration . With the relatively high surface evaporation of around 700 mm per year (with 500 mm of precipitation per year, for comparison: 1000 mm on the coast), which is caused by the regularly occurring strong winds of the highlands and temperatures of up to 30 degrees Celsius in summer, the maximum 50 cm deep lake dried up very often.

Quartz-containing feldspar from the eroded rocks and rocky soil in the area was fed into the depression by wind and rain and formed the sediment floor of the lake. There were also halites ( rock salts ) and ostracods (shellfish). A higher proportion of phyllosilicates (sheet silicates) such as muscovite , kaolinite and chlorite in the sediments of the lake compared to the surrounding rocks is due to the specific transport of the material into the depression.

The pH content of the full lake is now almost 9, whereas the salt content of the lake water is only 1/4 to 1/3 of the content in the Pacific Ocean and shows that the salt supplied comes primarily from the aerosols of the ocean , which in the Rainwater is concentrated in the lake.

According to Jacobson, it is assumed that with the current salt content of the lake and the specific route of salinization, around 20,000 previous replenishment and evaporation cycles were necessary to form the salt lake as it is today. Since the lake does not dry out completely every year, its age can be estimated at well over 20,000 years.

Vegetation and wildlife

A 2000 Department of Conservation study found that New Zealand's salt plant ecosystem is one of the clearest examples of the loss in New Zealand's ecosystem.

In the report in question, Sutton Salt Lake was defined as a special ecosystem with its 15 different and cataloged halophytes (salt plants) and due to its peculiarity.

Few animals live in the barren landscape around the lake. The most noticeable of these are the waterfowl , including the white-cheeked heron ( Egretta novaehollandiae ), the South Island oystercatcher ( Haematopus finschi ), the mallard ( Anas platyrhynchos ) and the paradise kasarka ( Tadorna variegata ), a duck bird native only to New Zealand. The Kelp Gull ( Larus dominicanus ) and the Black Swan ( Cygnus atratus , also called) Black Swan, have been sighted there.

use

The salt lake was developed as an attraction of New Zealand and the region for tourism . There is an approximately 4 km long one-hour circular hiking trail to the lake, which leads through a bizarre rock landscape. The number of annual visitors is manageable due to the remoteness of the lake. The area around the lake is often used by the locals for duck shooting and is also widely used as pasture for sheep and cattle.

environmental issues

Sutton Salt Lake is not particularly protected. There are no guidelines for hikers or tourists entering the unique ecosystem . But the main threat to the ecosystem comes from roaming cattle and sheep, who trample them and cause damage. Furthermore, the burning of cleared wood by the farmers in the area and the fertilization of the fields cause additional damage.

literature

  • Dave Craw, S. Beckett: Water and sediment chemistry of Sutton Salt Lake, east Otago, New Zealand , New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38: 315–328, The Royal Society of New Zealand, Wellington 2004

Web links

Individual evidence

  1. ^ AD Jacobson, JD Blum, CP Chamberlain, D. Craw, PO Koons: Climatic and tectonic controls on chemical weathering in the New Zealand Southern Alps , Geochimica et Cosmochimica Acta 67: 29-46, Dunedin, New Zealand, 2003.
  2. ↑ Geoff Rogers, Allan Hewitt, J. Bastow Wilson: Ecosystem-based conservation strategy for Central Otago's saline patches , Department of Conservation, Wellington 2000, ISBN 0-478-22013-8

Coordinates: 45 ° 34 ′ 35 ″  S , 170 ° 5 ′ 11 ″  O